Have you checked the documentation about creating dynamic module selectors
When you select the dynamic module selector option, we give you a template for the content type. You need to replace the developer name of the dynamic module and the dynamic module content type. If you are not sure what you need to enter there, you can go to your module and then go to its code references like described in the documentation.
If this does not fix the error, please consider sending us your widget and designer to test it locally.
All the best,
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items